Export (0) Print
Expand All

ParallelEnumerable::ToLookup<TSource, TKey> Method (ParallelQuery<TSource>, Func<TSource, TKey>)

Creates an ILookup<TKey, TElement> from a ParallelQuery<TSource> according to a specified key selector function.

Namespace:  System.Linq
Assemblies:   System.Linq.Parallel (in System.Linq.Parallel.dll)
  System.Core (in System.Core.dll)

[ExtensionAttribute]
public:
generic<typename TSource, typename TKey>
static ILookup<TKey, TSource>^ ToLookup(
	ParallelQuery<TSource>^ source, 
	Func<TSource, TKey>^ keySelector
)

Type Parameters

TSource

The type of elements of source.

TKey

The type of the key returned by keySelector.

Parameters

source
Type: System.Linq::ParallelQuery<TSource>

The sequence to create a ILookup<TKey, TElement> from.

keySelector
Type: System::Func<TSource, TKey>

A function to extract a key from each element.

Return Value

Type: System.Linq::ILookup<TKey, TSource>
A ILookup<TKey, TElement> that contains keys and values.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type ParallelQuery<TSource>. When you use instance method syntax to call this method, omit the first parameter. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).

ExceptionCondition
OperationCanceledException

The query was canceled with the token passed in through WithCancellation.

ArgumentNullException

source or keySelector is a null reference (Nothing in Visual Basic).

AggregateException

One or more exceptions occurred during the evaluation of the query.

.NET Framework

Supported in: 4.6, 4.5, 4

.NET Framework Client Profile

Supported in: 4

Portable Class Library

Supported in: Portable Class Library

Supported in: Windows Phone 8.1
Show:
© 2015 Microsoft